In my issued U.S. Pat. No. 3,861,930, entitled CONSTRUCTION MATERIAL, issued Jan. 21, 1975, I disclose a construction material which is a cementitious product produced from a combination of cracked outer layer of calcium sulfate and an inner core of calcium oxide, such material being particularly adapted for making plaster or blending with other products to make cementitious products and the like. In the present invention, it is desired to improve the quality of cementitious products by improving the curing rate and mechanical strength properties of cementitious products by more efficiently mechanically interlocking the material in the form of cracked fly ash and the chemically reactive lime, Linfan, Linvein, or cement.
Fly ash is a fine residue which is a by-product of the burning of powdered coal collected from the stacks of power plants and other coal-burning installations by mechanical means, or by electrostatic precipitators and the like. It consists of a finely divided hollow particulate material high in siliceous, ferrous, and aluminous material and is reactive with lime to form a cementitious material. However, such material, in order to be adaptable for the uses of the present invention, is in need of having a high surface to volume ratio, and should have reactive surfaces either at the outer surface or below the surface reactive with lime, cement, Linfan, or Linvein. In order to bring this about, the fly ash is cracked by a continuous process or by batch process, by which the material is elevated in temperature and rapidly quenched to ambient or below ambient temperature. It is the finished quality of this cracked fly ash which makes it particularly adapted for use in this invention. This invention also has to do with the particular method and apparatus for effecting this quenching by a continuous and economical process.